Objective The objective of this laboratory exercise is for you to write a GUI ba

Question

Objective
The objective of this laboratory exercise is for you to write a GUI based mathematical calculator using many of the Swing GUI components you have learned about in class.

Specifications
A base set of calculator functionality will be described, leaving the specific design and implementation up to you. Additional functionality will be listed as extras to improve you grade.

Base Functionality (worth a "B" grade)
Provide addition, subtraction, multiplication and division of floating point numbers
Provide a 10 digit keypad corresponding to the digits 0 - 9 to be used to enter numbers
Provide a decimal point ( . ) key so floating point numbers can be entered
Provide a field in which the number being entered will appear as well as the result of the operation
Provide 4 buttons for the 4 mathematical operations
Provide a = button to generate and display the results
Additional Functionality (to increase your grade)
Provide one or more memories
Provide additional mathematical functions
Handle unary operators ( +, -)
Handle (recover from) invalid input
Allow specification of the number of decimal places to be displayed
Use 1 or more components not covered in class - radio buttons, menus etc.
Enhanced visual presentation via colors, fonts etc.
Anything else you think will enhance the calculator

Explanation / Answer

//plx rate......thanks import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.text.*; public class CalculatorApplication extends JFrame implements ActionListener { JTextField resultField; double operandOne; double operandTwo; int operator; JButton addButton; JButton subtractButton; JButton multiplyButton; JButton divideButton; JButton percentileButton; JButton equalsButton; JButton dotButton; JButton cancelButton; JButton onebyButton; JButton backButton; JButton one1; JButton two2; JButton three3; JButton four4; JButton five5; JButton six6; JButton seven7; JButton eight8; JButton nine9; JButton zero0; Object source; public static void main(String[] args) { CalculatorApplication app = new CalculatorApplication(); app.addWindowListener(new WindowAdapter() { public void windowClosing(WindowEvent we) { System.exit(0); } }); app.setSize(280, 240); app.setVisible(true); } public CalculatorApplication() { super(); JPanel operandPanel; JPanel buttonPanel1; JPanel buttonPanel2; JPanel buttonPanel3; JPanel buttonPanel4; Container cp; cp = getContentPane(); cp.setLayout(new GridLayout(5, 1)); operandPanel = new JPanel(); operandPanel.setLayout(new FlowLayout()); resultField = new JTextField("0", 23); resultField.setHorizontalAlignment(SwingConstants.RIGHT); operandPanel.add(resultField); cp.add(operandPanel); buttonPanel1 = new JPanel(); buttonPanel1.setLayout(new FlowLayout()); seven7 = new JButton(" 7 "); seven7.addActionListener(this); buttonPanel1.add(seven7); eight8 = new JButton(" 8 "); eight8.addActionListener(this); buttonPanel1.add(eight8); nine9 = new JButton(" 9 "); nine9.addActionListener(this); buttonPanel1.add(nine9); divideButton = new JButton(" / "); divideButton.addActionListener(this); buttonPanel1.add(divideButton); cancelButton = new JButton(" C "); cancelButton.addActionListener(this); buttonPanel1.add(cancelButton); cp.add(buttonPanel1); buttonPanel2 = new JPanel(); buttonPanel2.setLayout(new FlowLayout()); four4 = new JButton(" 4 "); four4.addActionListener(this); buttonPanel2.add(four4); five5 = new JButton(" 5 "); five5.addActionListener(this); buttonPanel2.add(five5); six6 = new JButton(" 6 "); six6.addActionListener(this); buttonPanel2.add(six6); multiplyButton = new JButton(" * "); multiplyButton.addActionListener(this); buttonPanel2.add(multiplyButton); backButton = new JButton(" B "); backButton.addActionListener(this); buttonPanel2.add(backButton); cp.add(buttonPanel2); buttonPanel3 = new JPanel(); buttonPanel3.setLayout(new FlowLayout()); one1 = new JButton(" 1 "); one1.addActionListener(this); buttonPanel3.add(one1); two2 = new JButton(" 2 "); two2.addActionListener(this); buttonPanel3.add(two2); three3 = new JButton(" 3 "); three3.addActionListener(this); buttonPanel3.add(three3); subtractButton = new JButton(" - "); subtractButton.addActionListener(this); buttonPanel3.add(subtractButton); onebyButton = new JButton("1/x"); onebyButton.addActionListener(this); buttonPanel3.add(onebyButton); cp.add(buttonPanel3); buttonPanel4 = new JPanel(); buttonPanel4.setLayout(new FlowLayout()); zero0 = new JButton(" 0 "); zero0.addActionListener(this); buttonPanel4.add(zero0); dotButton = new JButton(" . "); dotButton.addActionListener(this); buttonPanel4.add(dotButton); percentileButton = new JButton(" % "); percentileButton.addActionListener(this); buttonPanel4.add(percentileButton); addButton = new JButton(" + "); addButton.addActionListener(this); buttonPanel4.add(addButton); equalsButton = new JButton(" = "); equalsButton.addActionListener(this); buttonPanel4.add(equalsButton); cp.add(buttonPanel4); } public void showResult() { boolean validOperands; DecimalFormat df = new DecimalFormat("0.00"); try { // operandOne = Double.parseDouble(operandOneField.getText()); // operandTwo = Double.parseDouble(operandTwoField.getText()); validOperands = true; } catch(NumberFormatException nfe) { validOperands = false; } if (validOperands) { if (source == addButton) { operandOne =Double.parseDouble(resultField.getText()); resultField.setText("0"); operator = 1; } else if (source == subtractButton) { operandOne =Double.parseDouble(resultField.getText()); resultField.setText("0"); operator = 2; } else if (source == multiplyButton) { operandOne = Double.parseDouble(resultField.getText()); resultField.setText("0"); operator = 3; } else if (source == divideButton) { operandOne = Double.parseDouble(resultField.getText()); resultField.setText("0"); operator = 4; } else if (source == percentileButton) { operandOne =Double.parseDouble(resultField.getText()); resultField.setText("0"); operator = 5; } else if (source == equalsButton) { operandTwo = Double.parseDouble(resultField.getText()); switch(operator){ case 1: resultField.setText(Double.toString(operandOne + operandTwo)); operandOne = 0.0; operandTwo = 0.0; break; case 2: resultField.setText(Double.toString(operandOne - operandTwo)); operandOne = 0.0; operandTwo = 0.0; break; case 3: resultField.setText(Double.toString(operandOne * operandTwo)); operandOne = 0.0; operandTwo = 0.0; break; case 4: if (operandTwo != 0.0){ resultField.setText(Double.toString(operandOne / operandTwo)); operandOne = 0.0; operandTwo = 0.0;} else{ resultField.setText("0");} break; case 5: resultField.setText(Double.toString(operandOne % operandTwo)); operandOne = 0.0; operandTwo = 0.0; } } else if (source == onebyButton) { if (resultField.getText().equals("0")) resultField.setText("0"); else resultField.setText(Double.toString(1.0 / Double.parseDouble(resultField.getText()))); } else if (source == one1) { if (resultField.getText().equals("0")) resultField.setText("1"); else resultField.setText(resultField.getText() + "1"); } else if (source == two2) { if (resultField.getText().equals("0")) resultField.setText("2"); else resultField.setText(resultField.getText() + "2"); } else if (source == three3) { if (resultField.getText().equals("0")) resultField.setText("3"); else resultField.setText(resultField.getText() + "3"); } else if (source == four4) { if (resultField.getText().equals("0")) resultField.setText("4"); else resultField.setText(resultField.getText() + "4"); } else if (source == five5) { if (resultField.getText().equals("0")) resultField.setText("5"); else resultField.setText(resultField.getText() + "5"); } else if (source == six6) { if (resultField.getText().equals("0")) resultField.setText("6"); else resultField.setText(resultField.getText() + "6"); } else if (source == seven7) { if (resultField.getText().equals("0")) resultField.setText("7"); else resultField.setText(resultField.getText() + "7"); } else if (source == eight8) { if (resultField.getText().equals("0")) resultField.setText("8"); else resultField.setText(resultField.getText() + "8"); } else if (source == nine9) { if (resultField.getText().equals("0")) resultField.setText("9"); else resultField.setText(resultField.getText() + "9"); } else if (source == zero0) { if (resultField.getText().equals("0")) resultField.setText("0"); else resultField.setText(resultField.getText() + "0"); } else if (source == dotButton) { if (resultField.getText().equals("0")) resultField.setText("0."); else if (resultField.getText().indexOf('.') == -1){ resultField.setText(resultField.getText() + "."); } else{} } else if (source == cancelButton) { resultField.setText("0"); } else if (source == backButton) { if (!(resultField.getText().equals("0") || resultField.getText().equals("0.0")) && resultField.getText().length() > 1){ resultField.setText(resultField.getText().substring(0,resultField.getText().length()-1)); } } } else resultField.setText("Invalid operand"); } public void actionPerformed(ActionEvent ae) { source = ae.getSource(); showResult(); } }

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